A storage apparatus capable of storing large-scale write data by managing a plurality of storage devices arranged in arrays by means of the RAID and controlling write accesses from a host computer has been known.
Recently, there has been a demand for integration of storage resources and consolidated management of the storage resources with respect to storage apparatuses. In order to fulfill such a demand, storage virtualization techniques are used.
One of the virtualization techniques is an external connection function. This external connection function is characterized in that another storage apparatus is connected to a primary storage apparatus via a Fibre Channel interface and a logical volume(s) of the other storage apparatus is mapped to a virtual volume(s) of the primary storage apparatus (Japanese Patent Application Laid-Open (Kokai) Publication No. 2007-114874).
Because of the external connection function, an administrator can operate and manage storage resources of the external storage apparatus connected to the primary storage apparatus in the same manner as internal storage devices of the primary storage apparatus. Therefore, even in an environment where pluralities of different types of storage apparatuses coexist, it is possible to realize unified data management; for example, it is possible to treat pluralities of different models of systems as if they were a single system. Also, the external connection function makes it possible to realize data migration operation between pluralities of different types of storage apparatuses in an integrated manner (Japanese Patent Application Laid-Open (Kokai) Publication No. 2006-072440).